Basic Chemistry
Atoms An atom is the smallest , indivisible part of a substance . 'Electrons' Electron is a Negatively charged fundamental Particle , which revolves around the nucleus around a fixed stationary energy level orbit . 'Protons' Proton is a Positively Charged Fundamental Particle , which is present in the nucleus . 'Neutrons' Neutron is a Neutral Fundamental Particle , present in the Nucleus 'Others' Positron , Quark , Neutrinos , Boson , Fermion , Leptons , etc. Atomic Number Atomic Number is the number of Electrons or Protons present in the Atom . Atomic Mass Number Atomic Mass is the sum total of the number of Protons and Neutrons (nucleons) in an atom . Atommic Mass Number is represented in terms of Unified Mass Unit which is equal to the mass of 1/12th of C12 atom (1 proton) . Mass of Proton = 1.6 x 10-24 g Mass of Electron = 9.1 x 10-28 g Mass of Neutron = 1.6 x 10-24 g Isotopes Atoms having the same atomic number , but different atomic masses are called as Isotopes . Isobars Atoms having the same atomic mass , but different atomic numbers are called as Isobars . Isotones Elements The fundamental , independent particles , which can be represented by a single atom are called as elements . Metals & Non Metals Electron Donating Species are called as Metals & Electron Withdrawing species are called as Non-Metals . Molecules A collection of atoms bonded together , is called as a molecule . Compounds A Compound is a molecule consisting of 2 or more atoms in its structure . Chemical Reactions A Chemical Reaction occurs when a Chemical Change occurs . Reactants react with each other under certain conditions with the help of catalysts to form products . Chemical Laws 'Law of Conservation of Mass' Law of Conservation of Mass states that mass is neither created nor destroyed in a Chemical Reaction . It is only converted from reactants to products . 'Law of Constant Proportions' The Law of Constant Proportions states that if a pure sample of a compound is formed by two reacting molecules , they will do so in a fixed ratio of their masses , independent of their source . 'Law of Multiple Proportions' The Law of Multiple proportions states that when two elements combine to form two or more products , the ratio of their masses is always the same or a whole number ratio of each other . 'Law of Reciprocal Proportions' The Law of Reciprocal Proportions states that if two different elements are combining with a third element , then the ratio in which they combine is either the same or a simple whole number ratio of proportion in which they combine with each other . Molecular Formula The Symbolic representation of a molecule or compound , so as to show the number of atoms of a particular element in the molecule is called as molecular formula . Empirical Formula The simplest ratio of a molecular formula is the Percentage Composition If the mass percentage is less than 100 , then the rest of the compound consists of Oxygen . The percentage composition consists of the percentage of mass occupied by each element in the molecule . Limiting and Excess Reagents Limiting reagents are taken in a limited quantity , while excess reagents are taken in excessive quantity . Stoichiometry Calculations based on mass - mass relation , volume - mass relation and volume - volume relation is called as Stoichiometry . The coefficients or number of moles obtained after balancing the reaction are called as stoichiometric coefficients .__FORCETOC__ Category:Chemistry